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Homosexuality - mutation? Evolutionary reasons.

Discussion of everything related to the Theory of Evolution.

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Homosexuality - mutation? Evolutionary reasons.

Postby Darwin420 » Mon Nov 17, 2008 7:11 am

Hey guys,

I started this topic so we could generate some interesting ideas and conversations. I haven't really read anything dealing with this topic as of yet. However, I do know that homosexual behaviour exists in other mammals so what do you guys think is the root of homosexual behvaiour? I was thinking if we assume that homosexual behaviour was derived from an allele and homosexual behaviour is favored in conditions where a population is over populating than that could be a reason why homosexual behaviour still exists (in humans). But then I realized using the theory of natural selection does not apply in this situation simply because we are talking about homosexual bahaviour - no zygote and no exchange of alleles therefore, these genes do not contribute to the gene pool.

So what do you guys think? Why is homosexuality still present in humans? I do realize to figure this out, using the theory of natural selection

If you got any input/articles/links regarding this topic, feel free to post. Look forward to your ideas.
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Re: Homosexuality - mutation? Evolutionary reasons.

Postby mcar » Wed Nov 19, 2008 12:25 am

I think that homosexuality in humans is more related to social factors. Recalling the theory of Erikson, certain stages in our life comes into conflict. If ever that conflict is not resolved, certain characteristic and behaviour modifications take place.
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Postby alextemplet » Wed Nov 19, 2008 1:10 pm

I agree. I do not think homosexuality is genetic. Although I admit that I, too, have not done much research into this topic, I would like to point out the high rate of homosexual behavior in prisons as an example that one's sexual orientation is dependent on environmental factors, and can even be changed once or more times throughout a person's life. As for natural selection reasons, I'm not sure that there are any. Perhaps in the prison case, it's a matter of the sex drive being so strong and there's no alternatives; this explanation may be extended to other species. If we were to investigate which individuals tend to be homosexual, and it turned out to be the ones least likely to get a heterosexual mate, then this hypothesis could hold up. Has anyone ever done research along those lines?
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Re: Homosexuality - mutation? Evolutionary reasons.

Postby Darwin420 » Wed Nov 19, 2008 7:31 pm

Valid point ALex regarding the prison example. However, I am not convinced. I believe it can be genetic. For example, my buddy kinda swings that way and I went to his buddies house which I found out later was a homosexual transvestite. But I found it really interesting analyzing this persons behaviour, he talked like a girl, his mannerisms were as of a girls, his interests and tastes were that of as a girl. Everything about this individual was feminine. What I ask is, if it wasn't a genetic disorder than do you really think an individual would choose to be gay? be harrassed for their oreintation?

I believe (hence "believe", because I don't have a lot of facts), that it is highly likely these behaviours are due to mutations in the brain. There has been evidence that suggest that when analyzing the hypothalamus in males and females we find that the size differs in sex. And what is the role of the hypothalamus?
pituitary gland regulation blood pressure regulation hunger and salt cravings
feeding reflexes thirst body temperature regulation
hydration heart rate bladder function
water preservation hormonal/neurotransmitter regulation ovarian function
testicular function mood & behavioral functions wakefulness
metabolism sleep cycles energy levels

I highlighted the functions that I think relate to this discussion.

That being said, it is also known (if you got more info on this send it) that the hypothalamus in homosexual males is that relative to the size of females. WHICH, can explain the feminine characteristics of gays which also relates to the guys behaviour that I described.

However, I do realize that using this hypothalamus example can't really explain this behaviour in females.

Any other input guys?
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Postby alextemplet » Thu Nov 20, 2008 1:29 am

You have a good point that no one would probably choose a homosexual lifestyle and face so much bigotry and discrimination. Well, some people might, but I'd be willing to be most won't. But as far as your guy-acting-feminine example, that doesn't have to be genetic. Behavior like that is learned at least as much as it is bred, if not more so. I wouldn't be surprised if no single factor was found responsible for homosexual (or, for that matter, heterosexual) tendencies. It might very well be a combination of both genetic and environmental causes.

I was thinking, a good way to test if it's cultural/behavioral would be to see if homosexuality is more common in cultures that are more accepting of it. However, this would be an almost impossible hypothesis to test, since I'm sure most homosexuality in oppressive societies goes unreported. Which leads us to what is probably the biggest obstacle when studying this behavior, and that is how do you study it? How do you even define it?

I like comedian Ron White's description of homosexuality as a relative thing, that we're all at least a little bit gay and it's just a question of to what extent are you gay. I won't go into explaining Ron White's arguments since they're a bit too vulgar for this forum, but you can look it up on YouTube if you're interested. A good example would be bisexuals. What category would they fall under? Many bisexuals also have a preference, tending to lean towards one gender while still occasionally going for the other. All in all it's a very tricky issue to study.
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Re: Homosexuality - mutation? Evolutionary reasons.

Postby Darwin420 » Thu Nov 20, 2008 11:23 pm

Yea, I agree that this is a very difficult area to study and there could be a variety of factors that could contribute to this. I agree with you that it could be social factors that cause this BUT I still believe it could be an innate thing. Ever talk to homosexuals that say "I feel like I am a woman trapped in a mans body"? These people claim that they always felt like a girl even at an early age where they demonstrated feminine behaviours. This is where the evidence for the size of the hypothalamus can be used to support my point. Like do you think social factors at that age would cause a kid to be gay? Do you think a toddler would choose that route and be ridiculed for a very long time. As you get older you tend (I find) to care less about what everyone else thinks and do your own thing, but I find when toddlers are younger they are trying to find the world and trying to find acceptance. I think cases like theses (the example I just gave) is a suitable example where a genetic disorder can be played.

But yes, I think this topic should be closed because it is a very difficult one to conclude, hard to test and numerous factors both social and genetic could cause this behaviour.
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Postby Darby » Fri Nov 21, 2008 3:28 am

Is it really that difficult to believe that attraction to a particular gender has a genetic component, and that some allele combinations might switch that attraction from what might be considered biologically normal?
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Re: Homosexuality - mutation? Evolutionary reasons.

Postby enarees » Fri Nov 21, 2008 5:53 am

The homosexual reproduction is the cause of "mutations"!

The homosexual reproduction is possible even among mammals - the secret is in male mammas(ribs :wink: ).
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Postby alextemplet » Fri Nov 21, 2008 7:52 am

Is it possible that there are different forms of homosexuality? For example, some caused by genetics and possible permanent, while others caused by environmental and social factors (and perhaps even by personal choice) that are more mutable?

As far as the gender identity issue, I'm going to throw in some humor and speak of the time when I was drunk that I said I was a lesbian trapped in a man's body. My friends and I still have good laughs over that one. :)
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Postby alextemplet » Fri Nov 21, 2008 10:49 am

If I may, I think the political aspects of this issue are also worthy of discussion. Although that isn't in the strictest definition a scientific question, this is one of those issues where politics and science become so intertwined that it's hard not to discuss the two of them at once.

It seems to me that there is a very strong desire, especially among the homosexual population, to believe that sexual orientation is almost completely genetic. The reason for this, I believe, is that if it is genetic then it is probably also not chosen and unchangeable. This would, in theory, entitle homosexuals to the same equal rights and legal protection from discrimination afforded to any other genetically-determined characteristic such as race or gender.

As for my own opinion, I don't think it matters politically whether homosexuality is caused by genes or something else. I think that as long as people are consenting adults, they should be free to do whatever sexual activities they want, so I think that homosexuals should be given equal rights anyway.

In response to your comment, Darby, I do not find it hard to believe that one's sexual orientation is genetic, but I am hesitant to believe that whole-heartedly because of the lack of evidence. If a specific gene or genes could be isolated and proven to be the cause of homosexual orientation, obviously the genetic argument would be very strong indeed. I think genes probably do have a lot to do with it, but I think other factors come into play as well. With very little supporting evidence for any of these explanations, it's very hard to tell which is which, especially given the difficulties in studying these issues mentioned above.
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Postby AstusAleator » Sun Nov 30, 2008 6:57 pm

If human homosexuality is genetic, wouldn't we see patterns of heredity just as in any other heritable genetic condition?

Unless it's a pre-existing genetic condition in ALL (or almost all) humans that is more of an on-off switch that gets flipped during embryonic development?

But if it was just an on-off switch we'd see frequency close to 50% - unless there's some mechanism inhibiting it.

If there's a mechanism inhibiting it, what triggers that mechanism to cease inhibiting? Is it developmental pathways or environmental?

It seems to me that homosexuality has somewhat of a scatter-shot abundance pattern throughout human populations - perhaps being more frequent in urban settings. It really does seem random, though.

All gay people I've known have asserted that they were always gay. There was no point at which they realized or decided they were gay (well except for a couple of girls in college that tended to go back and forth...)

So if a person has always been gay (as long as they remember) then it must either be genetic, or a developmental trigger during early life, or both.

My theory is that higher population density triggers a higher rate of homosexuality - but how exactly would that work in embryonic stages? It would have to be due to some sort of stress response in the mother. Some chemical generated in the mothers body as a response to high population density and all of the threats, competition, and social stress that come along with it. That's my theory and I'm stickin to it - for now.
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Postby alextemplet » Sun Nov 30, 2008 8:33 pm

Psychological factors might even play a role. If the mother is aware of the environment where she lives (high population density, etc.), there might be a subconcious mechanism to make the child homosexual. This might explain the high rate in urban areas.

Although, urban areas also tend to be more accepting, so the rate might be just as common in rural areas, but go unreported due to gays choosing to "stay in the closet" to avoid persecution and such.

All in all it's a really hard subject to study.
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